[The significance of soluble IL-2 receptors in rheumatoid arthritis with interstitial pneumonia].

Interstitial pneumonia is well known as one of the complications of rheumatoid arthritis (RA). While interleukin-2 (IL-2) regulates the immune response through IL-2 receptor (IL-2R), the exact role of the soluble form of IL-2R (sIL-2R), recognized as a part of the alpha chain or IL-2R, is still obscure. So, the immunological significance of sIL-2R in serum and in bronchoalveolar lavage fluid (BALF) of those of RA patients with or without interstitial pneumonia was studied. The sIL-2R was measured with an ELISA kit (T-Cell Science Ltd). The levels of sIL-2R in the sera of RA patients without interstitial pneumonia were significantly higher than those of normal controls. Furthermore, the levels of sIL-2R showed a statistically significant correlation with ESR and Lansbary's index. The levels of sIL-2R of RA patients with interstitial pneumonia were higher than in those without interstitial pneumonia although the evaluation of class and stage of arthritis in those RA patients with or without interstitial pneumonia revealed no significant difference. A high sIL-2R/albumin ratio in BALF of RA patients with interstitial pneumonia was shown in comparison with those of normal control. These data indicate that the estimation of sIL-2R in RA patients could be useful in estimating the disease activity and that high levels of sIL-2R reflect the active immune response in the lungs of RA patients with interstitial pneumonia.